The Onsrud 66-400 Series is the cardboard routing tool that lasts longer and delivers a better finish. If you face challenges routing Falcon Board, BioBoard, or other similar materials used for graphic display boards, you should be using this compression spiral bit. The cutting edge pattern has been optimized for shearing cardboard honeycomb core. The compression style flute has been configured for optimal finish and the innovative coating keeps the cutting edge sharper, longer.